How does chemotherapy work?

Understanding how chemotherapy works

Chemotherapy works by killing cells that are rapidly dividing, such as cancer cells, with the use of anti-cancer (cytotoxic) drugs. There are many different kinds of chemotherapy medicines and treatment plans available. The kind of medicines given and how often they are needed, will depend on the type of cancer you have, how it responds to treatment, and how your body responds and copes with treatment.

The following information will help you better understand your chemotherapy treatment, how it works, and answers to some common questions you may have.

What is cancer?

To understand how chemotherapy works, it is helpful to understand what cancer is and how cancer cells grow.

The human body is made up of billions of cells, which in a healthy body are usually turning over slowly, in an organised way. Cancer is the term we use for a disease that occurs when these cells grow in an abnormal and uncontrolled way. This uncontrolled growth of cells can causes a lump or a mass to form. We call this a tumour.

Tumours can be benign or malignant. Benign tumours usually grow slowly and do not spread to other parts of the body. Benign tumours only become a problem if they grow very large, taking up space and affecting the way the body works.

Malignant tumours are usually faster growing and can destroy tissue and have the ability to spread to other parts of the body.Cancer may also affect blood cells, causing blood cancers such as leukaemia, lymphoma or myeloma. These blood cancers also cause normal blood cell production to be reduced due to the uncontrolled growth of the abnormal (malignant) cells in the bone marrow.

Over time, the uncontrolled growth of cancer cells usually becomes too much for the body to cope with, or will spread to a part of the body that is essential for life. Chemotherapy treatment aims to control cancer, or even cure it.

Chemotherapy is the use of cytotoxic drugs to destroy these fast growing cancer cells. Cytotoxic means toxic to cells. A cytotoxic drug is a substance that results in cell damage or cell death.

During the chemotherapy process, the chemotherapy drug enters the blood stream and circulates throughout the body, targeting rapidly dividing cells. Cancer cells multiple much more often than most healthy cells, which is why chemotherapy is more likely to target and kill them. Chemotherapy may be given orally, through a needle inserted into the vein (known as an intravenous catheter), directly into the organ or tissues affected by the cancer, or as a cream.

What about healthy cells?

Unfortunately, as well as killing cancer cells, chemotherapy does affect our normal, healthy cells that are fast growing. This includes; hair, finger nails, skin and bone marrow. This damage to healthy cells is usually what causes some of the most common side effects of chemotherapy.

However, unlike cancer cells, normal cells can usually repair the damage and will recover with time. Cancer cells can’t recover from chemotherapy, and over the course of treatment will eventually die

How is Chemotherapy given?

Chemotherapy is usually given in multiple courses (cycles) for a set amount of time, or for as long as the treatment is effective. Having the treatment in cycles allows time for the healthy cells in your body to recover between treatments. This rest period allows the healthy cells in your body to recover from the cytotoxic drug effects.

There are many different kinds of chemotherapy medicines and treatment plans available. The kind of medicines given, and how often they are needed, will depend on the type of cancer you have, how it responds to treatment, and how your body responds and copes with treatment.

Chemotherapy at Icon

Chemotherapy may be used on its own, or in combination with other types of treatment, such as before or after surgery or radiation therapy. There are also other anti-cancer therapies available such as immunotherapy and targeted therapy. These work differently to chemotherapy but may be given in combination with chemotherapy drugs.

Our doctors stay up to date with the latest treatments and advances to recommend the right approach for you and your cancer. At Icon, we will talk your through your treatment plan and why it’s the best possible approach for you.

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Frequently asked questions

Chemotherapy are agents that interfere with cancer cells at the cellular level to slow or stop their growth. Chemotherapy or ‘chemo’ interferes with the process of cell growth and division. While this affects both normal and cancer cells, normal cells have a greater ability to repair damage and continue living. There is really no difference to that of normal cells – the main difference is that cancer cells grow continuously.
To be able to get into the bloodstream as rapidly as possible, many cytotoxic medicines are given by injection directly into a vein (intravenous injection). Some chemotherapy medicines can be taken orally as tablets or liquids.
A chemotherapy cycle is a course of chemotherapy usually followed by a rest period that allows the healthy cells time to recover. This sequence or cycle is repeated over a period of time varying from 2 to 4 weeks to 6 months or more. Chemo cycles vary according to the medication used and cancer types being treated, and the individual response of the patient.
Chemotherapy can be given as a single medication, but it is often given in combination with several different chemotherapy medications for maximum effect. Using several different medications targets and kills cancer cells using different mechanisms and therefore, there is a greater likelihood that cancer cells will be destroyed. It can also decrease the chances that a cancer or tumour may become resistant to the treatment.
Chemo medications work by targeting the fast-growing cancer cells. When chemotherapy medications are present in the blood stream, they can affect other normal fast-growing cells in the body, for example hair follicles and cells in the mouth and gastrointestinal tract causing side effects. Blood forming cells in the bone marrow may also be affected. It is normal to worry about this part of the treatment, but most side effects can be effectively managed. Side effects are very individual and may affect some people more than others.

The content on the Icon Cancer Centre website is for informational purposes only and should not be considered medical advice. It is not a substitute for consultation with a qualified medical practitioner. For personalised medical guidance, please consult with your GP or another qualified healthcare provider.